Apparatus, and computer program product for implementing vertically coupled noise control through a mesh plane in an electronic package design

ABSTRACT

A method, apparatus and computer program product are provided for implementing vertically coupled noise control through a mesh plane in an electronic package design. Electronic package physical design data are received. Instances of vertically coupled noise in the electronic package physical design data are identified. The identified instances of vertically coupled noise are quantified. Then the electronic package physical design data are modified to limit the vertically coupled noise.

FIELD OF THE INVENTION

The present invention relates generally to the semiconductor devices,and more particularly to a method, apparatus and computer programproduct for implementing vertically coupled noise control through a meshplane in an electronic package design.

DESCRIPTION OF THE RELATED ART

Electronic packages typically include multiple layers or planesincluding multiple signal, voltage and ground planes. Some electronicpackages utilize a mesh structure to construct what appears to bevoltage or ground plane. The mesh structure is needed to allow enoughnon-metal area to insure proper joining or lamination of the planestructures.

When designing an electronic package that must utilize a mesh plane,such as, for a power plane or a ground plane, many times the adjacentsignal traces may line up with holes in the mesh rather than on the meshlines. In some cases the signal lines may not line up on the mesh linesdue to its relative placement in the escape from the chip, or due to thesignal line escaping diagonally across the mesh openings.

A signal line disposed above or below mesh holes in the mesh plane has adifferent characteristic impedance than a signal line disposed directlyabove or below a mesh trace. Signal crosstalk also may occur to agreater extent through the mesh holes to signal traces disposed above orbelow the mesh holes.

U.S. patent application Ser. No. 10/632,183, to Bartley et al., filedJul. 31, 2003 and assigned to the present assignee, discloses a method,apparatus, and computer program product provided for creating customizedmesh planes in electronic packages. Electronic package physical designdata is received and signal traces in each adjacent plane to a meshplane are compared with the mesh layout. Signal traces adjacent to meshholes are identified. One or more fill methods are selected to modifythe mesh layout to replace selected mesh holes with added mesh structurealigned with the identified signal traces.

Coupled noise transferred vertically through a mesh plane in anelectrical package design is difficult to quantify on a net-by-netbasis. Current techniques are very prone to human error as well as aninefficient way of solving this problem.

High frequency use of mesh planes have typically been utilized inceramic first level packages. An industry trend is beginning where highspeed interfaces may also be routed on flex cables, which include meshplanes as references for increased flexibility. There are also instancesinside a laminate First Level Package where a reference plane is a meshplane due to design constraints.

As design margin becomes tighter as bandwidths increase; a need existsfor a mechanism that enables understanding, quantifying and limitingvertically coupled noise control through a mesh plane in an electronicpackage design.

SUMMARY OF THE INVENTION

A principal aspect of the present invention is to provide a method,apparatus and computer program product for implementing verticallycoupled noise control through a mesh plane in an electronic packagedesign. Other important aspects of the present invention are to providesuch method, apparatus and computer program product for implementingvertically coupled noise control through a mesh plane in an electronicpackage design substantially without negative effect and that overcomemany of the disadvantages of prior art arrangements.

In brief, a method, apparatus and computer program product are providedfor implementing vertically coupled noise control through a mesh planein an electronic package design. Electronic package physical design dataare received. Instances of vertically coupled noise in the electronicpackage physical design data are identified. The identified instances ofvertically coupled noise are quantified and the electronic packagephysical design data are modified to limit the vertically coupled noise.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention together with the above and other objects andadvantages may best be understood from the following detaileddescription of the preferred embodiments of the invention illustrated inthe drawings, wherein:

FIGS. 1 and 2 are block diagram representations illustrating a computersystem and operating system for implementing vertically coupled noisecontrol through a mesh plane in an electronic package design inaccordance with the preferred embodiment;

FIG. 3 is a flow chart illustrating exemplary sequential steps forimplementing vertically coupled noise control through a mesh plane inaccordance with the preferred embodiment;

FIG. 4 is a diagram illustrating an exemplary signal plane above a meshplane in an electronic package;

FIG. 5 is a diagram illustrating an exemplary signal plane below a meshplane in an electronic package;

FIG. 6 is a diagram illustrating the exemplary signal planes of FIGS. 4and 5 together without a mesh plane in the electronic package;

FIG. 7 is a diagram illustrating the exemplary signal planes of FIGS. 4and 5 together with an initial mesh plane in the electronic package;

FIG. 8 is a diagram illustrating the exemplary signal planes of FIGS. 4and 5 together with an exemplary resulting mesh plane minimizingvertically coupled noise control in the electronic package; and

FIG. 9 is a block diagram illustrating a computer program product inaccordance with the preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, in FIGS. 1 and 2 there is shown acomputer system generally designated by the reference character 100 forimplementing methods for vertically coupled noise control through a meshplane within electronic packages in accordance with the preferredembodiment. Computer system 100 includes a main processor 102 or centralprocessor unit (CPU) 102 coupled by a system bus 106 to a memorymanagement unit (MMU) 108 and system memory including a dynamic randomaccess memory (DRAM) 110, a nonvolatile random access memory (NVRAM)112, and a flash memory 114. A mass storage interface 116 coupled to thesystem bus 106 and MMU 108 connects a direct access storage device(DASD) 118 and a CD-ROM drive 120 to the main processor 102. Computersystem 100 includes a display interface 122 coupled to the system bus106 and connected to a display 124.

Computer system 100 is shown in simplified form sufficient forunderstanding the present invention. The illustrated computer system 100is not intended to imply architectural or functional limitations. Thepresent invention can be used with various hardware implementations andsystems and various other internal hardware devices, for example,multiple main processors.

As shown in FIG. 2, computer system 100 includes an operating system130, an electronic package design program 132, a vertically couplednoise control program 134 of the preferred embodiment, and a userinterface 136. Manufacturing design limitation rules 140 are stored inaccordance with the vertically coupled noise control methods of thepreferred embodiment.

Various commercially available computers can be used for computer system100, for example, an IBM personal computer. CPU 102 is suitablyprogrammed by the vertically coupled noise control program 134 toexecute the flowchart of FIG. 3 for implementing vertically couplednoise control through a mesh plane within electronic packages inaccordance with the preferred embodiment.

In accordance with features of the preferred embodiment, methods areprovided for implementing vertically coupled noise control through amesh plane within electronic packages that are more efficient, moreaccurate and easier to solve than conventional processes that are bothprone to human error and generally inefficient in solving this problem.The method and vertically coupled noise control program 134 of thepreferred embodiment allows the user to either have the program 134 fixthe coupled noise problem or the user to manually provide corrections.Methods of the preferred embodiment include moving signal traces andadding additional mesh to the mesh layer between the existing traces forreducing coupled noise.

In accordance with features of the preferred embodiment, methods areprovided for identifying, quantifying and limiting instances ofvertically coupled noise through a mesh plane in electrical packagedesign. The user of the vertically coupled noise control program 134 ofthe preferred embodiment has the flexibility to set coupled noisethresholds as well as specifying the preferred mechanisms or noisecoupling reduction methodology for reducing the coupling; i.e., movingthe signal traces or filling in the mesh. This method and apparatus ofthe preferred embodiment uses these inputs along with the electricaldesign file to either regenerate the design file with fixes in place, ornotify the user on the locations and severity of the coupled noise. Thisis accomplished either through a gradient visual representation of thehotspots of coupling, or through an ASCII text file with X,Y coordinatesalong with coupling values.

Referring to FIG. 3, there are shown exemplary steps performed by thecomputer system 100 for implementing methods for vertically couplednoise control through a mesh plane within electronic packages inaccordance with the preferred embodiment. Electronic and packagephysical design data or system design inputs for a module packagearrangement are received as indicated in a plurality of blocks 300, 302,304, 306, and 308 and applied to an analysis tool input file asindicated in a block 310.

Received system design inputs include a design file at block 300, a listof victim nets at block 302, a coupled noise design target at block 304,a manual or automatic fix selection at block 306, and a couplingreduction methodology at block 308. The analysis tool input file atblock 310 is coupled to a package vertical coupled noise identificationengine 312 that identifies victim nets without looking at mesh coverage.

Next a coupled noise quantification engine 313 quantifies noise couplingwith a mesh plane, for example, using one or more of lookup tables, acomprehensive math equation, and/or a dump to a field-solver. Then allthe nets are compared to the coupled noise design target as indicated ina block 314. If all the nets are less than the coupled noise designtarget, then a log file is stored as indicated in a block 316. Thiscompletes the exemplary operations as indicated in a block 318.

Otherwise, if all the nets are not less than the coupled noise designtarget, then a user friendly output is generated as indicated in a block320, for example, indicating the locations and severity of the couplednoise through a gradient visual representation of the hotspots ofcoupling, or through an ASCII text file with X,Y coordinates along withcoupling values. Checking for a manual or automatic fix selection isprovided as indicated in a block 322. If a manual selection isidentified, then the user friendly output is stored as indicated in ablock 324. Then the exemplary operations are completed as indicated in ablock 326.

If an automatic fix selection is identified, then a design file couplingreduction engine as indicated in a block 328 receives physical designfile constraints as indicated in a block 330, such as mesh fill densitylimitations, conductor/via proximity, and impedance limitations. Anupdated design file is generated as indicated in a block 332 responsiveto the user selected coupling reduction methodology of moving signaltraces or adding additional mesh to the mesh layer between the existingtraces for reducing coupled noise. Also a combination of both movingsignal traces and adding additional mesh to the mesh layer between theexisting traces for reducing coupled noise can be used to generate theupdated design file at block 332. Then a temporary input file isgenerated as indicated in a block 334 and applied to the packagevertical coupled noise identification engine at block 312. Then theexemplary operations are repeated for the temporary input file generatedat block 334.

FIGS. 4-8 show an example of instances of where the method and programof the preferred embodiment identifies coupling through the mesh plane.The program determines an optimal solution for reducing coupled noisebased up limitations of the design parameters. A pair of arrows in eachof the FIGS. 4-8 points to the traces exhibiting coupled noise for thisexample.

Referring now to FIGS. 4 and 5, in FIG. 4 there is shown an exemplarysignal plane generally designated by reference character 400 to bepositioned above a mesh plane (not shown) in an electronic package. FIG.5 illustrates an exemplary signal plane generally designated byreference character 500 to be positioned below a mesh plane (not shown)in an electronic package. Signal lines representing signal routing plane400 above the mesh reference are shown in solid lines, with dotted linesrepresenting signal routing plane 500 below the mesh.

Referring now to FIG. 6, there is shown an exemplary structure generallydesignated by reference character 600 including the exemplary signalplanes 400 and 500 of FIGS. 4 and 5 together without a mesh plane in theelectronic package. In FIG. 6, the wiring layers only shown where thevertically coupled noise control program 134 of the preferred embodimentadvantageously can move the respective signal traces of signal planes400 and 500 of FIGS. 4 and 5 to minimize coupling A typical packagedesign can have multiple instances of this structure throughout thedesign.

Referring now to FIGS. 7 and 8, in FIG. 7 there is shown an exemplarystructure generally designated by reference character 700 including theexemplary signal planes 400 and 500 of FIGS. 4 and 5 together with aninitial mesh plane in the electronic package. In FIG. 8 there is shownan exemplary structure generally designated by reference character 800including the exemplary signal planes of FIGS. 4 and 5 together with anexemplary resulting mesh plane minimizing vertically coupled noisecontrol in the electronic package. In FIG. 8, the wiring and mesh layersare shown where the vertically coupled noise control program 134 of thepreferred embodiment advantageously has added more mesh to minimizecoupling.

Referring now to FIG. 9, an article of manufacture or a computer programproduct 900 of the invention is illustrated. The computer programproduct 900 includes a recording medium 902, such as, a floppy disk, ahigh capacity read only memory in the form of an optically read compactdisk or CD-ROM, a tape, a transmission type media such as a digital oranalog communications link, or a similar computer program product.Recording medium 902 stores program means 904, 906, 908, 910 on themedium 902 for carrying out the methods for implementing verticallycoupled noise control through a mesh plane within electronic packages ofthe preferred embodiment in the system 100 of FIGS. 1 and 2.

A sequence of program instructions or a logical assembly of one or moreinterrelated modules defined by the recorded program means 904, 906,908, 910, direct the computer system 100 for implementing verticallycoupled noise control through a mesh plane of the preferred embodiment.

While the present invention has been described with reference to thedetails of the embodiments of the invention shown in the drawing, thesedetails are not intended to limit the scope of the invention as claimedin the appended claims.

1-10. (canceled)
 11. Apparatus for implementing vertically coupled noisecontrol through a mesh plane in an electronic package design comprising:an electronic package design program receiving electronic packagephysical design data; a vertically coupled noise control programidentifying instances of vertically coupled noise in the electronicpackage physical design data; said vertically coupled noise controlprogram quantifying the identified instances of vertically couplednoise; responsive to the quantified identified instances of verticallycoupled noise, receiving physical design file constraints, said physicaldesign file constraints including mesh fill density limitations,conductor/via proximity, and impedance limitations; and generating anupdated design file including modifying the electronic package physicaldesign data for limiting the identified instances of vertically couplednoise including selectively adding mesh to a mesh layer between signaltraces adjacent to the identified instances of vertically coupled noisefor reducing vertically coupled noise, and selectively moving signaltraces for reducing vertically coupled noise.
 12. Apparatus forimplementing vertically coupled noise control as recited in claim 11wherein said received electronic package physical design data includesone of more user selections of a target design level for verticallycoupled noise; a noise coupling reduction methodology; a manual orautomatic design fix; and a list of victim nets.
 13. Apparatus forimplementing vertically coupled noise control as recited in claim 11wherein said vertically coupled noise control program generates anoutput indicating the locations and severity of the vertically couplednoise. 14-15. (canceled)
 16. A computer program product embodied oncomputer readable storage medium for implementing vertically couplednoise control in electronic packages in a computer system, said computerprogram product including instructions executed by the computer systemto cause the computer system to perform the steps of: receivingelectronic package physical design data; identifying instances ofvertically coupled noise in the electronic package physical design data;quantifying the identified instances of vertically coupled noise;responsive to the quantified identified instances of vertically couplednoise, receiving physical design file constraints, said physical designfile constraints including mesh fill density limitations, conductor/viaproximity, and impedance limitations; and generating an undated designfile including modifying the electronic package physical design data forlimiting the identified instances of vertically coupled noise includingselectively adding mesh to a mesh layer between signal traces adjacentto the identified instances of vertically coupled noise for reducingvertically coupled noise, and selectively moving signal traces forreducing vertically coupled noise.
 17. A computer program product forimplementing vertically coupled noise control as recited in claim 16wherein the step modifying the electronic package physical design datafor limiting the identified instances of vertically coupled noiseincludes the steps of identifying a user selected noise couplingreduction methodology. 18-19. (canceled)